Edwaed james duff



(No Model.)

B. J. DUFF. STEAM BOILER AND ITS FURNACE.

i No. 439,814. v Patented Nov. 4, 1890.

M! I"! I n Y r Im/etfiforr Q I a 23 1. E1 Z i X W Ljw mm H We "om: warns a. nm-ummfwumnamn, a. c.

UNITED STATES PATENT OFFICE.

'FDWARD JAMES DUFF,OF GLASGOW, SCOTLAND.

STEAM-BOILER AND ITS FURNACE.

SPECIFICATION forming part of Letters Patent No. 439,814, dated November 4, 1890.

Application filed May 20, 1890.

Serial No. 352,485. (No model.)

To all whom it may concern:

Be it known that I, EDWARD JAMES DUFF, a subject of the Queen of Great Britain and Ireland, and a resident of Glasgow, in the county of Lanark, Scotland, haveinvented certain new and useful Improvements in Steam- Boilers and their Furnaces, (forwhich a British patent has been applied for, No. 5,487, April 11, 1890,) of which the following is a specification. This invention has for its object to obtain increased efficiency with absence of smoke in connection with steam-boilers and their furnaces.

The invention is applicable to various kinds of steam-boilers. It is, however, shown on an accompanying sheet of explanatory drawings as applied to a common type of land-boiler, comprising a horizontal cylindrical shell, with two furnaces in fines extending from end to end of the boiler.

Figure l is a front end elevation, but with fire-doors and some other parts removed; and Figs. 2 and 3 are longitudinal Vertical and horizontal sections.

In the drawings the same reference-numerals are used to mark the same or like parts wherever they are repeated.

The grate of each furnace of the boiler consists of a series of longitudinal tubes 5, of steel or other suitable metal, these tubes being inclined so as to be higher at their inner ends and being fixed in outer and inner end castings 6 7 of steel or iron. Access to the grate-tubes 5 for cleaning out or withdrawing them is given through apertures in the end castings 6 7 at the sides opposite to the ends of the tubes, those of the inner end casting 7 being closed by screw-plugs 8, while those of the outer or front end casting 6 are closed by caps 9, (not shown in Fig. 1,) fixed by bolts securing them to internal cross-pieces. I Either the screw-plugs 8 or the caps 9 may be used for both end castings 6 7. Each inner end casting 7 is connected bya central vertical pipe 10 to the interior of the boiler through the top of the fiue-tube 11, and a hanging or depending bridge or wall 12 of fire-brick (not shown in Fig. 1) is fixed across the upper part of the flue-tube. The outer or front end castings 6 of the two furnaces are connected to curved branches 13 of a pipe 14,

communicating through the front end plate 15 of the boiler with the interior. The branch pipes 13 are provided with downward continnations 16, which are fitted with stop-cocks (not shown) and are to be used for blowing off, so as to wash out the grate-tubes 5 whenever it may be thought desirable. The arrangement of the pipes 13 14: is such as to allow of slight movements of the parts of the grate, which may be caused by variations of temperature without any part being injuriously strained. In consequence of the front and back ends of the grate-tubes 5 being connected, respectively, to lower and higher parts of the interior of the boiler, a vigorous circulation of the water takes place through the grate-tubes toward their inner ends, and this circulation is further promoted by the inclin ation of the grate-tubes.

:Beneath the grate-tubes 5 there is in each case a transverse partition 17, and in the space 18 from this partition to the front end of the grate-tubes air passes up between the grate-tubes and through the fuel lying upon them; but in the space 19, at the inner side of the partition 17, the gases pass downward between the grate-tubes, and thence onward along the flue. The fuel is placed on the gratetubes 5, so as to extend from their front ends inward beyond the partition 17,but not close up to the hanging bridge 12, a division consisting of a fire-brick bar 20 being placed across the grate-tubes 5, so as to keep a space 21 at their inner ends clear of fuel and so that a portion of the gases may pass downward between them without being obstructed by the fuel. Vith the arrangements which have been described the gases from the fuel at the outer part of the furnace are compelled to take a downward course at the inner part, partly through some fuel, but chiefly through the space 21 at the inner ends of the gratetubes, and in consequence of this downward course of the fuel gases they pass in close con tact with the incandescent fuel at the inner part of the furnace, and their combustible c011- stituents are thoroughly ignited and the production of smoke prevented. By providing the comparatively free space 21 at the extreme inner end of the furnace for the downward passage of a portion of the fuel gases there is avoided the great resistance to the flow of the gases, which has been the cause of inefficiency in attempts to make the whole of the fuel gases pass downward through fuel.

The transverse partition 17 beneath the grate tubes 5, between the spaces 18 19, is provided with a door 22, through which ashes may be withdrawn, and if found advantageous a regulated supply of air may be admitted through the partition. Ordinary firedoors 23 (not shown in Fig. 1) are fitted at the front ends of the furnaces above the gratetubes 5, and air may be admitted through regulated openings in these doors.

The apparatus may be modified by arranging the space 21at the inner end of the furnace for the free passage of a portion of the fire gases beyond the extreme ends of the grate-tubes 5, and in that case the said space, having no tubes across it, may be reduced in size.

The air may be supplied by ordinary draft What I claim as my invention, is

In a steam-boiler furnace having a water- 25 tion and arranged substantially as and for 35 the purposes hereinbefore described.

In testimony whereof I have signed my name to this specification in the presence of two subscribing Witnesses.

EDWARD JAMES DUFF.

Witnesses:

EDMUND HUNT, DAVID FERGUSON. 

